This stuff is always interesting, but some of the conclusions the researchers or (more likely) other people draw amount to "oh, we'll just take everything above $XX,000; it's not like you'll miss it anyway." That's probably just my paranoia kicking in :)
Also, you (or the article) didn't mention the relationship between income and the second kind of happiness, the "life evaluation." IIRC, your emotional well-being takes a huge hit when you have kids, so there's clearly something big missing there or else all parents are fools.
Finally, as a comedian (Louis CK, I think) once said, "it's hard to be unhappy on a jet ski."

Despite popular assertions to the contrary, science tells us that money can buy happiness. To a point. Recent research has begun to distinguish two aspects of subjective well-being. Emotional well-being refers to the emotional quality of an individual's everyday experience — the frequency and...